Marslang for Visual Studio Code

Language support for Marslang: .mars files are recognised as their own language, highlighted, and checked by the interpreter itself.

What it does

• Syntax highlighting for keywords, fixed/hot/cold bindings, type annotations, families and their methods, @Decorator markers, takepkg imports, error families, strings with escapes, and comments.
• Hover over a name to see what it is: a function, family, or method shows its signature and its @Decorator.docstring; a variable shows its type, noting when that type comes from its first value rather than an annotation. Built-ins, std.Error families, and decorator markers are described too.
• Diagnostics from marslang check, shown where the error is. The interpreter reports the source line for syntax and import errors; for an error it cannot place, such as unknown name 'nope', the extension marks where that name is used.
• Snippets for the shapes you write repeatedly: m, func, family, private, run, for, takepkg.
• Marslang: Run File, which runs the open file in a terminal, also on the editor's run button.

Checking needs the interpreter. Install it with one command from marslang.kevin-z.com, or point marslang.path at a build. Without it, highlighting still works and the extension says so once.

Settings

A file is checked as it is on disk, so a diagnostic follows a save rather than each keystroke.

Install from source

npm install
npm test
npm run package
code --install-extension marslang-0.3.0.vsix

npm test tokenizes test/sample.mars with the same TextMate engine VS Code uses and asserts the scopes themes colour, runs the real interpreter over broken programs and checks that each error lands on the line it belongs to, and checks what hovering each kind of name in the sample shows. Point MARSLANG at a build to use a specific interpreter; checks that need a newer interpreter than the one found are reported as skipped.

Press F5 in this repository to launch a VS Code window with the extension loaded and the sample open.

Hover

Hover reads marslang symbols, added in rs-0.11.0, over the current text of the file, unsaved edits included. With an older interpreter, hovering still describes built-ins, but not your own declarations.

Lines in error messages

The interpreter reports positions from rs-0.9.1 onward. With rs-0.9.0 the diagnostics still appear, but every error without a position is placed on the name it quotes, or on the first line.

License

Marslang is source-available under the Marslang Source License, not an open source license. In short:

• Use it, and share unmodified copies free of charge, for any noncommercial purpose.
• Change it only to prepare a contribution, such as a pull request.
• Programs you write in Marslang are yours, to use and license however you like.
• Commercial use, and anything else the license does not cover, needs the author's written permission: open an issue to ask.